Recovery boilers are used in various processes, such as manufacturing paper. Some of the organic products used in the process are flammable. Instead of discarding this waste material, it may be burned as a fuel for the boiler. The inorganic chemicals are collected at the bottom of the furnace and are discharged through dedicated openings in the lower furnace into a dissolving tank.
FIG. 1 shows a prior art recovery boiler system 3. Initially a fuel, such as natural gas, is released from gas jets 9 of a burner 7 and ignited. They create combustion in combustion chamber 11.
After the boiler system 3 heats up enough, then fuel is sprayed through fuel nozzles 13 into combustion chamber 11. This fuel may be the organic waste product such as that referred to as “black liquor” created in the paper manufacturing process. Therefore, throughout this document, it is to be understood that fuels nozzles may also be referred to as “liquor guns”.
The heated flue gasses rise and heat pipes 5 filled with water. Any smelt from burning other materials will form in the bottom of boiler system 3 and run into a dissolving tank 17.
The droplet size of the fuel sprayed from nozzles 13, the spray pattern, the location where the fuel is introduced, the temperature of the combustion chamber 11 when the fuel was introduced and other factors have an effect on the amount of combustion produced, the subsequent temperature at different locations in the combustion chamber 11, the stability of the combustion and the emissions produced. Therefore, the droplet size and spray distribution of the fuel is very important. Many of these factors are determined by the nozzle design.
The prior art discloses simple fuel nozzles such as the type described in U.S. Pat. No. 4,462,319 issued Jan. 31, 1984 to Larsen. This descried the use of fuel nozzles for recover boilers and relies on the use spray holes to define droplet size. Larsen does not address the positioning of fuel nozzles to regulate the combustion to meet some of the needs listed above.
Currently, there is a need for a fuel nozzle system that allows a user to adjust the location where fuel is sprayed and the distribution of fuel droplets sprayed to increase efficiency and reduce the amount of unwanted pollutant gases created, such as NOx.